The present invention relates to an apparatus and method for examining images, and more particularly, to an image examination apparatus for determining a character as a subject of examination as to good/not-good, on the basis of an image obtained by shooting a character or the like as a subject of examination.
In the process to print predetermined characters, symbols or the like, such as product name and type, serial number, date, etc. (hereinafter, referred merely to as characters) on the product or package thereof, there is a need for a process to examine the result of print and check for improper printing, such as blurs and distortions.
The methods for automating the examination process as above include a disclosure, e.g., in JP-A-11-283039. In the conventional image examining apparatus, an imaging device previously reads out a well-quality character to register a preferred character image. Then, a character as a subject of examination is read out of the imaging device, to determine a difference in brightness at portions between registered character image and the examination image, to detect as a differential image a portion that the difference of brightness is in excess of a predetermined threshold.
It is assumed that, for example, a good image “0” is registered as a registered image 1 as shown in FIG. 1. In this case, if an examination image 2 be also shot as a good image similarly to the registered image 1, a differential image 3 will not appear as shown in the figure, thus determining the examination image 2 good (OK). On the contrary, if the examination image 2 has a break-off or blur in a lower part of the character “0” as shown in FIG. 2, the broken or blurred part is detected as a differential image 3. Thus, the examination image 2 is determined not-good (NG).
However, the image examining apparatus like this uses the determination criteria different from the criteria of determination by the human, e.g. in image differential area, thus making possible to compare between the characters different in size. However, where the registered image 1 and the examination image 2 are different in font as shown in FIG. 3 or any one is in italic or bold as shown in FIG. 4, a differential image 3 appears to determine an examination result inconveniently as not-good. Consequently, each time the character or font is changed, it is required for the image examining apparatus to read out the quite same image as the examination image 2 by the imaging device and previously store it as registered image 1.
The use of the image examining apparatus makes possible to automate the examination process. However, there is troublesome operation in reading a character as a subject of examination from the imaging device and registering it as in the above manner each time the subject of examination is changed. Excepting special symbols and marks, it is desired to readily input and register a character as a subject of examination through an input unit, such as a keyboard or console.
However, as long as the examining character is inputted on an input unit without having an imaging function, such as a keyboard or console, (or without using the imaging function), there is a need to determine the character in such a range as can be read by the human. For a character 5 different in size from a standard character 4 as shown in FIG. 5, tilted character 6, character 7 different in linewidth (in the entire or a part), italic character 8, non-continuous character (slightly broken as compared to the entire character) 9, character 10 different in character width and so on, it is desired to determine a presence or absence of improper print due to break-off, blur or the like while determining the same character as the standard character 4 and allowing the difference in font or the like.
Meanwhile, there is, as a character recognition technology, a disclosure in JP-A-7-65126. This technology, a technology for unknown character recognition, could not have been used in the application of collation, examination or the like to recognize an existing character as to good/not-good.